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4. HDS Multisystem > Dermatopathology > Flashcards

Dermatopathology Flashcards

1
Q

Skin

Functions

A
  • Protective barrier against mechanical, thermal and physical injury as well as noxious agents
  • Prevents loss of moisture
  • Reduces harmful effects of UV radiation
  • Acts as a sensory organ
  • Helps regulate temperature control
  • Plays a role in immunological surveillance
  • Synthesizes vitamin D3 (cholecalciferol)
  • Has cosmetic, social, and sexual associations
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2
Q

Skin

Layers

A
  • Epidermis
    • External layer
    • Mainly composed of layers of keratinocytes
    • Also containing melanocytes, Langerhans cells and Merkel cells
    • Basement membrane
    • Multilayered structure forming dermal-epidermal junction
  • Dermis
    • Area of supportive connective tissue between epidermis and underlying subcutis
    • Contains sweat glands, hair roots, nervous cells and fibers, blood and lymph vessels
  • Subcutis
    • Layer of loose connective tissue and fat beneath dermis
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3
Q

Epidermal

Layers

A
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4
Q

Acantholysis

A

Loss of intercellular cohesion between keratinocytes

Loss of cell-cell adhesion

Ex. Pemphigus

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5
Q

Regular

Acanthosis

A

↑ in thickness of epidermis

Regular ⇒ all rete pegs descend to same level

Ex. Psoriasis

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6
Q

Irregular

Acanthosis

A

↑ in thickness of epidermis

Irregular ⇒ rete pegs descend to different levels in papillary dermis

Ex. Lichen Simplex Chronicus

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7
Q

Civatte/Colloid Bodies

A

Pink, globular remnants of keratinocytes

Ex. Lichen Planus

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8
Q

Epidermal Atrophy

A

↓ thickness of epidermis

Ex. Actinic Keratosis

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9
Q

Dyskeratosis

A
  • Abnormal, premature keratinization w/in cells below stratum granulosum
  • Corps rond ⇒ rounded nucleus w/ halo of pale to pink dyskeratotic cytoplasm
  • Grain ⇒ dark blue flattened nucleus surrounded by minimal dyskeratotic cytoplasm
  • Ex. Darier’s Disease
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10
Q

Erosion

A

Loss of epidermis

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11
Q

Exocytosis

A
  • Lymphocytes in epidermis w/ associated spongiosis
  • Term usually used when discussing spongiotic dermatitis
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12
Q

Hydropic Swelling

(Ballooning)

A
  • Intracellular edema of keratinocytes
  • Often seen in viral infections
    • Ex. Herpes Simplex
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13
Q

Hyper-/Hypogranulosis

A

↑/↓ granular layer

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14
Q

Hyperkeratosis

A

Thickening of stratum corneum

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15
Q

Lentiginous Melanocytic

Growth Pattern

A

Linear pattern of melanocyte proliferation w/in epidermal basal cell layer

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16
Q

Papillomatosis

A
  • Surface elevation caused by hyperplasia and enlargement of contiguous dermal papillae
  • Finger-like projections
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17
Q

Parakeratosis

A
  • Keratinization w/ retained nuclei in stratum corneum
  • On mucous membranes, parakeratosis is normal
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18
Q

Spongiosis

A

Intercellular edema in epidermis w/ stretching of cell-cell junctions

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19
Q

Freckle (Ephelis)

Overview

A
  • Small, well-defined, pigmented macules
  • 1–2 mm in diameter
  • Predilection for face, arms, and shoulder regions of fair-skinned individuals
  • Appear at an early age and may follow an episode of severe sunburn
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20
Q

Freckle (Ephelis)
Histopathology

A

↑ melanin pigment w/in basal keratinocytes ⇒ Hyperpigmentation of freckles

Melanocytes are normal in number and morphology

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21
Q

Lentigo Simplex

A
  • Brown macule w/ an early age of onset
  • Little or no relationship to sun exposure
  • Hyperpigmented
  • Often elongated rete ridges
  • Usually w/ ↑ melanocytes
  • No nests of melanocytes
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22
Q

Benign Melanocytic Nevi

Overview

A

Junctional, Compound, or Intradermal nevus:

  • Junctional Nevus
    • Brown to black macule w/ melanocytic nests at junction of epidermis and dermis
  • Compound Nevus
    • Brown papule w/ combined histologic features of junctional and intradermal nevi
  • Intradermal Nevus
    • Skin-colored or light brown papule w/ nests of melanocytes in dermis
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23
Q

Benign Melanocytic Nevi
Histopathology

A
  • Epidermal changes vary greatly
  • Atrophy, hyperplasia, papillomatosis or horn cysts may be present
  • Nests at dermal-epidermal junction and/or in dermis
  • Bilaterally symmetrical & sharply defined
  • Individual cells mature
    • Important in distinguishing some benign nevi from melanomas (usually show little or no maturation)
    • Superficial nevus cells are larger
      • Tend to produce melanin
      • Grow in nests
    • Deeper nevus cells are smaller
      • Produce little or no pigment
      • Appear as cords and single cells
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24
Q

Seborrheic Keratoses

Overview

A
  • Common benign lesions
  • Typically begin to appear during 4th decade of life
  • Tan to black macular, papular or verrucous lesions
    • Solitary or multiple
    • Often have a waxy, velvety or verrucous, ‘stuck-on’ appearance
    • Large variation in clinical appearance
  • May simulate melanocytic neoplasms
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25
Q

Leser–Trélat

Sign

A
  • Abrupt ↑ in size or number of seborrheic keratoses
  • Paraneoplastic cutaneous marker associated w/ an internal malignancy
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26
Q

Seborrheic Keratoses

Histopathology

A
  • Epidermal proliferation
  • Variable combinations of hyperkeratosis, papillomatosis, acanthosis
  • Keratinocytes often appear basaloid
  • Often have pseudo-horncysts
  • “Pseudo” b/c they connect to surface and represent papillomatosis
  • Often abundant melanin in basal layer or throughout epidermis
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27
Q

Skin Tag / Acrochordon / Fibroepithelial Polyp

A
  • Skin-colored to brown papules of eyelids, neck, axilla or groin
  • Often pedunculated
  • Very common
  • ↑ incidence w/ aging and obesity
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28
Q

Skin Tag

Histopathology

A
  • Pedunculated papule
  • Epidermis often extends almost completely around specimen when sectioned
  • Papillomatosis and acanthosis common
  • ± Epidermal atrophy
  • Dermis consists of loose CT that is often pale
  • Dilated blood vessels common
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29
Q

Cysts

Overview

A
  • Walled-off cavity filled w/ keratin, mucin or fluid
  • Classified based on location, contents, type of epithelial lining, and adnexa presence
  • Clinical manifestation:
  • Firm, well-circumscribed, dermal or subcutaneous nodules
  • Often moveable
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30
Q

Epidermal Inclusion

Cyst

A
  • Contains lamellated keratin
  • Lined by squamous epithelium
  • Sometimes flattened w/ a granular layer
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31
Q

Pilar or Trichilemmal

Cyst

A
  • Contains amorphous, dense and compact, homogenized keratin
  • Lined by squamous epithelium
  • Keratinocytes are often pale
  • There is no granular layer
  • Calcification common w/in cyst
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32
Q

Dermoid

Cyst

A
  • Wall commonly resembles epidermoid cyst
  • Lined by squamous epithelium
  • Contains multiple appendages budding outward from its wall
    • Small hair follicles
    • Sebaceous glands
    • Eccrine glands
    • Apocrine glands
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33
Q

Steatocystoma

A
  • Cyst wall consists of rugated squamous epithelium
  • Wrinkled eosinophilic refractile cuticle of keratin instead of a granular layer
  • Sebaceous glands w/in or adjacent to cyst wall, opening into cyst
  • Only “true” sebaceous cyst
34
Q

Actinic Keratosis

Overview

A
  • Common, precancerous ill-defined white-red papule
  • Found in sun-damaged areas
  • low-grade atypia of epithelium vs precursor lesion to early low-grade carcinoma in situ
  • analogous lower grade lesion of intraepithelial neoplasia seen in cervix or vulva
35
Q

Actinic Keratosis
Histopathology

A
  • Often hyperkeratosis
  • Sometimes ulceration
  • Parakeratosis especially overlying atypical keratinocytes
  • Partial-thickness atypical keratinocytes
  • Nuclear pleomorphism
  • Atypical mitosis
  • Disordered maturation
  • Often spares epidermis above adnexa
  • Solar elastosis in dermis
36
Q

Squamous Cell Carcinoma In Situ

Overview

A

“Bowen’s disease”

  • Common hyperkeratotic erythematous plaque
  • Often crusted on sun-exposed or covered skin
  • Full-thickness atypia of epidermal keratinocytes over a broad zone
37
Q

Squamous Cell Carcinoma In Situ
Histopathology

A
  • Parakeratosis, hyperkeratosis, acanthosis
  • Atypical keratinocytes with
  • Nuclear pleomorphism
  • Atypical mitosis
  • Disordered maturation throughout epidermis (all layers)
  • Atypical keratinocytes have not invaded through BM of dermal-epidermal junction
38
Q

Squamous Cell Carcinoma

Overview

A
  • Second most common type of skin cancer
  • Red papule, nodule or plaque
  • Often hyperkeratotic or ulcerated
39
Q

Squamous Cell Carcinoma
Histopathology

A
  • Invasion of dermis by atypical keratinocytes
  • Cells w/ nuclear pleomorphism, atypical mitosis and disordered maturation
  • Keratinocytes enlarged w/ abundant ground-glass eosinophilic cytoplasm
  • ± Polymorphous inflammatory infiltrate
40
Q

Basal Cell Carcinoma

Overview

A
  • Most common type of skin cancer
  • Pearly erythematous papule w/ rolled border
  • Usu. on head and neck region
  • Long-standing lesions often large, locally destructive, and ulcerated ⇒ “rodent ulcer”
41
Q

Melanoma

Overview

A
  • Malignant tumor arising from melanocytes
  • Usually presents as:
    • Enlarging, irregularly pigmented macule, papule, or plaque
    • Asymmetric w/ irregular borders
  • ↑ Incidence and mortality rates of melanoma in recent decades
  • Early detection important in melanoma management
42
Q

Melanoma
Histopathology

A
  • Epidermis normal, atrophic or hyperplastic
  • Ulceration means worse prognosis
  • Asymmetrical proliferation of melanocytes
  • Often w/ poorly demarcated border
  • Atypical melanocytes
    • Small, spindled or epitheloid
    • Often finely dusted w/ melanin
    • Arise at dermal-epidermal junction
    • Invade the dermis
    • Pleomorphism, hyperchromatism, ↑ mitoses and ± prominent nuclei
    • Poor maturation of melanocytes
  • Deeper cells are just as large and atypical as superficial one
  • Pagetoid spread (or buckshot scatter) of melanocytes w/in epidermis
  • Lymphocytic infiltrate at base common
  • Depth of invasion into dermis ⇒ Breslow’s thickness
    • Most important prognostic factor
43
Q

Basal Cell Carcinoma
Histopathology

A
  • ± Ulceration of epidermis
  • Basaloid tumor cells
  • Buds from epidermis or follicles or found w/in dermis
  • Variable atypia
  • Stroma often separates from tumor ⇒ Retraction artifact
  • Peripheral palisading of nuclei
  • Mucin in stroma or w/in basaloid aggregates
44
Q

Tumors of the Dermis

A
45
Q

Dermatofibroma

Overview

A
  • Common benign fibrohistiocytic tumors of the skin
  • Firm dermal papules that “dimple” when the adjacent skin is compressed
46
Q

Dermatofibroma
Histopathology

A
  • Epidermal hyperplasia
  • Flattened “tabled” rete ridges or basaloid proliferation
  • Hyperpigmented basal layer
  • Poorly circumscribed proliferation of boomerang-shaped spindled fibroblasts or histiocytes in the dermis
  • Often w/ whorled appearance
  • Large bundles of collagen (“keloidal collagen”) often present at periphery of lesion
  • Fibroblast around the bundles ⇒ “collagen trapping”
47
Q

Cellular Migrant

Skin Tumors

A
  • Proliferative disorders of the skin involving cells whose progenitors arise elsewhere
  • Hone in to the cutaneous microenvironment
48
Q

Cutaneous T-Cell Lymphomas (CTCL)

Overview

A
  • Primary cutaneous disorders that arises from lymphocytes
  • Mycosis fungoides (MF) ⇒ most common type of CTCL
    • Accounts for ~ 50% of all primary cutaneous lymphomas
  • Classical MF ⇒ progress from patch stage → plaque stage → tumor stage
  • Long clinical course over years or even decades
49
Q

CTCL
Histopathology

A
  • Early lesions ⇒ band-like infiltrate of slightly atypical lymphocytes
    • Line up along the dermal–epidermal junction
  • As lesions progress ⇒ progressive epidermotropism of atypical lymphocytes
    • Epidermotropism = lymphocytes residing in the epidermis
    • Often exhibits a peripheral halo
  • Numerous lymphocytes w/in the epidermis w/ minimal spongiosis
  • Focal collections of intraepidermal atypical lymphocytes ⇒ Pautrier microabscesses
    • Most specific finding
    • Only in 10% of lesions
  • Atypical lymphocytes sometimes have cerebriform nucei
  • Tumor stage ⇒ less epidermotropism and atypical lymphocytes diffusely fill the dermis
50
Q

Urticaria

Overview

A
  • Transient skin or mucosal swellings due to plasma leakage
  • Wheals are characteristically pruritic and pink or pale in the center
51
Q

Urticaria
Histopathology

A
  • Epidermis normal
  • Dermal edema
  • Sparse perivascular and interstitial eosinophils, lymphocytes, PMNs and/or mast cells
52
Q

Eczematous Dermatitis

Overview

A
  • Diseases under umbrella category of “eczematous dermatoses”
  • Similar clinical and histological presentations
  • Eczema means to “boil over” and is synonymous w/ dermatitis
  • Spongiotic inflammation of the epidermis ⇒ common unifying characteristic
53
Q

Eczematous Dermatitis

Diseases

A
  • Allergic contact dermatitis
  • Asteatotic dermatitis
  • Atopic dermatitis
  • Autosensitization (ID) reaction
  • Dyshidrotic eczema
  • Irritant contact dermatitis
  • Nummular dermatitis
  • Seborrheic dermatitis
  • Venous stasis dermatitis
54
Q

Eczematous Dermatitis
Histopathology

A
  • Hallmark is spongiosis ⇒ exocytosis of lymphocytes and intercellular edema
  • ± Spongiotic vesicle (more likely if clinically acute)
  • Focal parakeratosis w/ ± crusting
  • PMNs in stratum corneum if secondarily impetiginized
  • Acanthosis or hyperkeratosis (more if clinically chronic)
  • Superficial perivascular lymphocytes, occasional eosinophils
55
Q

Erythema Multiforme

Overview

A
  • Most commonly associated w/ herpes simplex virus (HSV) infection
  • Typical clinical presentation includes “target” lesions
  • Oral mucosa, dorsal hands, or palms frequently involved
  • Episodes are recurrent and self-limited
56
Q

Erythema Multiforme
Histopathology

A
  • Necrotic keratinocytes
  • ± Spongiosis
  • Rarely intraepidermal vesicles
  • Basal layer liquefaction w/ ± subepidermal blister
  • Edema of the papillary dermis
  • Perivascular or interface lymphocytes, rarely w/ eosinophils
57
Q

Chronic Inflammatory Dermatoses

A

Inflammatory skin disorders that persist for many months to years

58
Q

Psoriasis

Overview

A
  • Chronic disorder
  • Results from a polygenic predisposition combined w/ triggering factor
    • E.g. Trauma, infections or medications
  • Sharply demarcated, scaly, erythematous plaques
  • ± Sterile pustules
  • Most common sites:
    • Scalp, elbows and knees
    • Nails, hands, feet and trunk (including intergluteal fold)
59
Q

Psoriasis
Histopathology

A
  • Confluent parakeratosis
  • PMNs in:
    • Stratum corneum ⇒ Munro microabscesses
    • Spinous layer ⇒ spongiform pustules of Kogoj
  • Hypogranulosis
  • Suprapapillary thinning of epidermis
  • Regular acanthosis, often w/ clubbed rete ridges
  • Dilated capillaries in dermal papillae
  • Auspitz sign ⇒ pinpoint bleeding if scale picked off
  • Perivascular lymphocytes
60
Q

Lichen Planus

Overview

A
  • “Pruritic, purple, polygonal, planar papules and plaques” of skin and mucosa
  • Fine reticulated scale over surface ⇒ Wickham’s striae
  • Hep C is more prevalent in pts w/ lichen planus vs controls
61
Q

Lichen Planus
Histopathology

A
  • Compact hyperkeratosis
  • No parakeratosis
  • Hypergranulosis, often wedge shaped
  • Irregular acanthosis w/ “saw-toothed” rete ridges
  • Colloid/civatte bodies
  • Dense, continuous infiltrate of lymphocytes along D-E junction
  • Liquefaction degeneration of the basal layer ⇒ ex. Of interface dermatitis
  • Melanin incontinence common
62
Q

Blistering (Bullous) Diseases

A

Classified by:

  • Level of the blister
  • Subcorneal, intraepidermal, subepidermal
  • Type of inflammatory cells involved
  • PMNs, lymphocytes, eosinophils
  • Mechanism of blister formation
  • Spongiosis, acantholysis, balloon degeneration or epidermolysis
63
Q

Pemphigus Vulgaris

Overview

A
  • Intraepidermal vesiculobullous disorder
  • Caused by auto-Ab directed at an intercellular keratinocyte adhesion protein ⇒ Desmoglein 3
  • Presents w/ flaccid bullae that break to form painful erosions
64
Q

Pemphigus Vulgaris
Histopathology

A
  • Split immediately above basal layer
  • Leaves a “tombstone row” of basal keratinocytes
  • Tracking of separation down hair follicles ⇒ “follicular extension”
  • ± Eosinophils in spongiotic foci or blister cavity
  • Superficial lymphocytic inflammatory infiltrate in dermis
  • ± Eosinophils in dermal infiltrate
  • Direct IF (DIF) shows “net-like” deposition of IgG and C3 between keratinocytes in lower epidermis
65
Q

Bullous Pemphigoid

Overview

A
  • Subepidermal vesiculobullous disorder
  • Caused by auto-Ab to bullous pemphigoid antigen I and/or bullous pemphigoid antigen II
  • Presents with:
    • Tense bullae on normal or erythematous skin
    • Urticarial/eczematous lesions
66
Q

Bullous Pemphigoid
Histopathology

A
  • Subepidermal bulla
  • Eosinophils typically present w/in blister cavity
  • Early lesions ⇒ ± eosinophilic spongiosis
  • Exocytosis of eosinophils w/in a mildly spongiotic epidermis
  • Direct IF of adjacent skin shows linear deposition of IgG and C3 along D-E junction
67
Q

Dermatitis Herpetiformis

Overview

A
  • Intensely pruritic vesiculobullous disorder
  • Lesions common on elbows, knees, buttocks, and scalp
  • Caused by auto-Ab vs epidermal transglutaminase-3
  • Disease is highly correlated w/ celiac sprue
68
Q

Dermatitis Herpetiformis
Histopathology

A
  • Subepidermal vesiculation
  • Neutrophilic abscesses in tips of dermal papillae
  • Slight fibrin deposition in tips of dermal papillae @ points of vesiculation
  • Direct IF shows granular deposition of IgA w/in dermal papillae
69
Q

Acne Vulgaris

Overview

A
  • Multifactorial disorder of the pilosebaceous unit
  • Significant psychologic and economic impact
  • Clinical manifestations include comedones, papules, pustules, cysts and scarring
  • Characterized by:
    • ↑ Sebum production
    • Follicular hyperkeratinization
    • Propionibacterium acnes
    • Inflammation
70
Q

Acne Vulgaris
Histopathology

A
  • Follicular plugging
  • Frequently ruptured pilosebaceous apparatus w/ suppurative inflammation
  • Sometimes abscesses, sinus tracts and fibrosis
71
Q

Panniculitis

A
  • Inflammation of the subcutaneous fat
  • Categorized into 2 groups:
    • “Septal” ⇒ primarily involves the septa separating lobules of fat
    • “Lobular” ⇒ primarily involves the lobules of fat themselves
72
Q

Erythema Nodosum

Overview

A
  • Painful, erythematous subcutaneous nodules
  • Usually distributed symmetrically over pretibial areas; occasionally elsewhere
  • Later stages ⇒ lesions acquire a bruise-like appearance
  • ± Fever, arthralgias and malaise
  • Associated w/ a wide variety of systemic disorders
73
Q

Erythema Nodosum
Histopathology

A
  • Septal panniculitis of lymphocytes, histiocytes, PMNs and/or eosinophils
  • Older lesions:
    • Multinucleated giant cells
    • Septal fibrosis
74
Q

Verrucae

Overview

A

“Warts”

  • Caused by human papillomavirus (HPV)
    • Ubiquitous DNA virus
    • Over 100 HPV subtypes
    • Different subtypes tend to produce different clinical lesions
  • Immunocompromised patients may have larger or more intractable warts
75
Q

Verrucae (Warts)
Histopathology

A
  • Hyperkeratosis, papillomatosis, hypergranulosis
  • Columns of parakeratosis
    • Especially over projecting dermal papillae
  • Vacuolated superficial keratinocytes w/ pyknotic raisin-like nuclei ⇒ koilocytes
  • Rete ridges shaped inward @ borders of lesion
  • Dilated capillaries in dermal papillae
  • Perivascular lymphocytes
76
Q

Molluscum Contagiosum

A
  • Caused by a DNA poxvirus of the Molluscipox genus
  • Mainly a disease of children
  • Can affect immunocompromised adults
  • Produces smooth, dome-shaped, umbilicated papules
77
Q

Impetigo Contagiosa

Overview

A
  • Common superficial infection w/ Staph aureus and/or Strep pyogenes
  • Most common in children
  • Plaques of honey-colored crust
78
Q

Impetigo Contagiosa
Histopathology

A
  • Early lesions ⇒ subcorneal pustule filled w/ PMNs ± acantholytic cells
  • Spongiosis common
  • Established lesions ⇒ crust composed of serum, PMNs and parakeratotic material
  • Gram-⊕ cocci usually found in crust
  • Gram stain and culture may be required
79
Q

Dermatophytosis (Tinea)

Overview

A
  • Caused by superficial fungi
  • Further subclassified based on area of the body affected
  • Most tinea infections are characterized by:
    • Intensely pruritic, annular lesions
    • Peripheral scale
    • Central clearing
    • Variable inflammation
80
Q

Dermatophytosis (Tinea)
Histopathology

A
  • ± PMNs in the stratum corneum
  • Parakeratosis common
  • Fungal hyphae in stratum corneum or follicles
  • Sometimes visible w/ H&E
  • Best seen w/ Periodic Acid–Schiff (PAS) stain
  • Rich in mucopolysaccharides ⇒ stain bright pink to red
  • Variable inflammatory response
  • Skin may appear “normal”
  • Culture of material scraped from these areas will usu. allow ID of offending species
81
Q

Pityriasis Versicolor

Overview

A
  • Superficial infection of the epidermis caused by commensal yeast of genus Pityrosporum
  • Some use the genus Malassezia to refer to the pathogenic hyphal phase of this normal skin commensal
  • Particularly common in young adults living in warm and humid climates
  • Hypopigmented or brownish-red, slightly scaly patches
  • Most common on the trunk

4. HDS Multisystem (43 decks)

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